On the Relationship between Preferential and Multilateral Trade Liberalization: The Case of Customs Unions

This paper analyzes a game of trade policy (called Bilateralism) between three countries in which each country chooses whether to liberalize trade preferentially in the form of a Customs Union (CU), multilaterally, or not at all. We also analyze a restricted version of this game (called Multilateralism) under which countries do not have the option to form CUs. The analysis sheds light on the relationship between multilateral and preferential trade liberalization as sanctioned by GATT Article XXIV. We find that when countries have symmetric endowments, global free trade can be achieved without permitting CUs. Allowing for asymmetry, we isolate circumstances where Article XXIV helps further the cause of multilateral liberalization as well as when it does not. Furthermore, we show that Article XXIV's stipulation -- that countries forming a CU not raise tariffs on outsiders -- fails to make multilateral liberalization any more attractive to countries. However, such a tariff restriction does lower the adverse impact of a CU on the non-member.